1. Field of the Invention
The present invention relates to amplifiers with operating points compensated for changes in temperature as well as for changes in supply voltage.
2. Description of the Prior Art
Differential amplifiers are commonly used in the art to provide a reliable and inexpensive means for furnishing amplification with low sensitivity to temperature or supply voltage variations. However, such amplifiers usually require relatively complex circuitry to accomplish both of these features.
Circuits similar to the present invention have been used to reduce temperature sensitivity problems, but such circuits have been highly sensitive to changes in supply voltages due to their particular operating conditions. Examples of such circuits appear in RCA application note ICAN-5296, FIGS. 6, 8 and 9. Other similar circuits are used in high fidelity complementary symmetry amplifiers as exemplified by RCA application note ICAN-6048, FIG. 7.
In contrast to such prior art circuits, the present invention is relatively simplistic, but yet is compensated to provide a low sensitivity to both temperature and supply voltage variations.